Kinetic Studies of<i>Micrococcus luteus</i>B-P 26 Undecaprenyl Diphosphate Synthase Reaction Using 3-Desmethyl Allylic Substrate Analogs
作者:Keitaro FUJIKURA、Yuji MAKI、Norimasa OHYA、Mikiya SATOH、Tanetoshi KOYAMA
DOI:10.1271/bbb.70723
日期:2008.3.23
In order to investigate the substrate binding feature of undecaprenyl diphosphate synthase from Micrococcus luteus B-P 26 with respect to farnesyl diphosphate and a reaction intermediate, (Z,E,E)-geranylgeranyl diphosphate, we examined the reactivity of artificial substrate analogs, 3-desmethyl farnesyl diphosphate and 3-desmethyl Z-geranylgeranyl diphosphate, which lack the methyl group at the 3-position of farnesyl diphosphate and Z-geranylgeranyl diphosphate, respectively. Undecaprenyl diphosphate synthase did not accept either of the 3-desmethyl analogs as the allylic substrate, indicating that the methyl group at the 3-position of the allylic substrate is important in the undecaprenyl diphosphate synthase reaction. These analogs showed different inhibition patterns in the cis-prenyl chain elongation reaction with respect to the reactions of farnesyl diphosphate and Z-geranylgeranyl diphosphate as allylic substrate. These results suggest that the binding site for the natural substrate farnesyl diphosphate and those for the intermediate allylic diphosphate, which contains the cis-prenyl unit, are different during the cis-prenyl chain elongation reaction.
为了研究来自藤黄微球菌 B-P 26 的十一异戊二烯基二磷酸合酶与法呢基二磷酸和反应中间体 (Z,E,E)-香叶基香叶基二磷酸的底物结合特征,我们检查了人工底物类似物 3-desmethyl 的反应性法呢基二磷酸和3-去甲基Z-香叶基香叶基二磷酸,其分别在法呢基二磷酸和Z-香叶基香叶基二磷酸的3-位上缺少甲基。十一异戊二烯二磷酸合酶不接受任何 3-去甲基类似物作为烯丙基底物,表明烯丙基底物 3 位的甲基在十一异戊二烯二磷酸合酶反应中很重要。相对于法呢基二磷酸和Z-香叶基香叶基二磷酸作为烯丙基底物的反应,这些类似物在顺式异戊二烯基链延长反应中表现出不同的抑制模式。这些结果表明,在顺式异戊二烯基链延长反应过程中,天然底物法尼基二磷酸盐和中间体烯丙二磷酸盐(含有顺式异戊二烯基单元)的结合位点是不同的。